Unloader



hetented Dec, 3%, lldfid,

vent

SH QWTDEII B. RLDFIELD, 0F EASTOIN, PENNSYLVANIA, ASSIGNOR TO IhTGEPISQLL-RAND QU'MPAN'Z', GE JERSEY CITY, NEW JERSEY, A. CORPORATION OF NEW JERSEY,

UNLOAIDER.

Application filed November 22, 19%. Serial No. 678,293.

To all whom it may concern Be it known that I, SNowonNB. Rnnvtnno, a citizen of the United States, and a resident of Easton, county of Northampton, and State of Pennsylvania, have invented a certain Unloader, of which the following is a specification accompanied by drawings.

This invention relates to unloading 1nechanisin for compressors, but more part culariy to that type of unloading mechanism which may be automatically or manually operated.

it has been found highly desirable to provide a compressor with a combined manually and pneumatically operated unloader. In starting a compressor, especially when the compressor is operated by an electric motor, it is essential that the compressor piston be able to start up under little or no load. lit there is siulicient rweiver pressure, one satisfactory manner of unioading is to enable the inlet valves to be held open by means 01 the receiver or discharge line pressure, and thus obtain automatic unloading. There-are times, however, when it is necessary to unload the compressor by hand, as for example when the receiver pressure is low, or when but partial unloading is desired, and this may be accomplished by holding open one inlet valve and allowing the remaining valves to function, In this manner partial unloading may be accomplished, and a less amount of fluid will be forced into the discharge line,

fine of the objects of this invention, is to improve on compressor unloaders byproducing an unloader which may be cheaply manufactured, is ruggedly constructed, readily applicable in an assembled condition to a compressor, and adapted to be either manually or neumatically operated.

Further obgeote ot' the invention will hereinafter appear, and the invention is shown in one of its preferred embodiments in the accoiunanying drawings, in which e 'l is a diagrammatic elevation, partly in vertical section of a compressor unit embodying the invention, and

Figure 2 is an enlarged detail vertical sectional view of the com oressor unloader shown in Figure It,

Referring to the drawings, the compressor A is provided with an inlet valve mechanism B, and discl'iarge valve mechanism G, and is formed with a cylinder D, in which a piston E having a piston rod F, is adapted to reciprocate, being operated from any suitable source of power, Fluid such as air, is supplied to the compressor cylinder D through the intake conduit G, and discharged into the receiver H thoughthe discharge line J. In this instance, the inlet valve mechanism B comprises a valve seat K, and guard L between which a plate valve 0 is clamped by the bolt l? and,nut Q, although it is to be understood that any suitable valve mechanisrn may be employed without departing from the scope of the present invention,

In accordance with the present invention, a cover Q, is secured to the compressor cylinder casing R by the bolts S, and a packing T is preferably interposed between the cover and the casing id, in order toitorm a iluid tight joint therebetween. The cover Q is preferably formed with an extension or hollow boss U in which is located a cylinder V, having less or extensions W, tenninating in a ring i/V which adapted to bear against the valve seat it, in order to hold the valve mechanism in place in the wall of the cylinder An annular flange is formed on the cylinder V and limits the inward movement of the cylinder in the cover Q in the assembly oi the parts, when the unloader is applied to the compressor.

A piston Y is in this instance slidabiy mounted in the cylinder *7, and is preferably formed with a plurality of integral fingers Z, which are adapted to bear against and unseatthe plate valve O. in order to form a seal between the cylinder i and the piston Y, a piston ring u may be provided in the piston An external annular flange Y is in this instance formed on the piston if so that the piston and ring will not slide out of the cylinder "i when the unloader is being assembled in the compressor. in order to hold the fingers Z noiinally away from the plate vaive U, a coil spring is tl'iis in: stance guided over the bolt F at one and bears at its other end against the inside ot end of the cylinder V.

the iston Y, thereby holding the piston no rmal y inits inward position in the cylinder V. A plate is in this instance secured to the cover Q? by the bolts d and closes one A packing e is pref- I erably located between the plate 0, .cover extension U and cylinder V, and is adapted .to be wedged tightly in place to prevent fluid, such as air or gas, from escaping from the compressor cylinder passage and unloader cylinder to atmosphere.*

In order to move the piston Y, manually, outwardly from the cylinder V and thereby move the fingers Z to hold the platevalve O in its open position, a plunger f provided with a hand wheel 9, is threaded into a nut lb carried by the plate 7. The end -of the plunger 7 extends through the plate 0, a short distance so that by screwing the plunger f inwardly, the piston Y and fin ers Z- will' be moved outwardly from the cy inder and the fingers will bear against and hold open the valve 0. A cap j is in this instance threaded on the nut hto hold the packing y" firmly in place about the plunger so that fluid is prevented from escaping o atmosphere from the cylinder V. I

In order to unload the compressor cyliner automatically by holding the inlet valves 0 in their open position, a passage 0 is preferably formed in the plate 0 and piping 12 connects the passage 0 with the receiver H. In order to regulate tlie-admisinits open position. As soon as the pressure in the receiver H has dropped below the point at which the auxiliary valve (1 has een set, the passage of air to the piston Y will be automatically shut oil' and the coil spring 6 will return the piston Y to its normal position. It is to be understood that any suitable auxiliary valve 9 may be employed .because any automatic auxiliary valve, which can be set for certain pressures in the receiver is included in the'scope of the present invention.

In order to obtain partial unloading, one of the auxiliary valves q may be set to operate at one pressure in the receiver and the' other auxiliary valve may be set .to operate at a higher pressure. In this manner, when the receiver pressure reaches a certain point, one of the auxiliary valves will operate to admitpressure fluid to one of the unloaders, but the other, unloader willnot be brought held open if desired. Whenever the un loaders are brought into operation, the fluid .drawn in on the suction stroke of the com-' pressor piston will be forced out to atmosphere on the compression stroke, and consequently no fluid will be forced into thereceiver. By mechanism as described considerable flexibilityis obtained so that the cover, plate and casing can be secured together to efi'ect an eflicient construction. fluid tight as to the unloader cylinder V and also the'inlet passage of the compressor cylinder. This construction makes this device applicable. not alone to air com res sors but to any other analogous type 01? machine, as an ammonia or other gas compressor.

I claim:

1 1. Unloading mechanism for compressors, comprising in combination, valve mechanism controlling the inlet to the compressor, a cover adapted to be secured to the compressor cylinder casing, a cylinder in the cover adapted to hold the valve mechanism in place in'the compressor cylinder wall,a

constructing the unloading piston in said cylinder having fingers adapted to unseat thecompressor valve, a plate secured to said cover and closing one end of said cylinder, a passage leading from the outside of the said plate to the space between said plate and said piston for admitting pressure fluidto/ the piston for unseating said valve, a spring for holding the piston normally in its inward position in said cylinder, sealing means between said cover plate. unloader cylinder and cover to prevent the escape of pressure fluid therebetween, and a manually operable plunger extending through said plate for actuating the.

piston to unseat the compressor valve.

2. Unloading mechanism for compressors comprising in combination, valve mechanism controlling theinlet to the compressor, a cover adapted to be secured to the compressor cylinder casing, a hollow boss formed onsaid cover, a cylinder slidable in said boss. extensions carried by said cylinder for holding the valve mechanism in place in the compressor cylinder wall, a stop on said cylinder for limiting the inward movement of the cylinder in said boss, a piston slidable in said cylinder having fingers adapted to bear against the compressor valve, a stop on said piston for limiting the inward movement of the piston in said cylinder, a spring in said piston for holding the piston normally in its initting pressure fluid to actuate said piston, inward position 1n the cylinder, a plate seand a manually operable plunger in said cured to said cover for holding the cylinder plate for actuating said piston to unseat the 1 in POSltlOIl, a packing interposed between compressor valve.

5 said plate, unloader cylinder, and cover for In testimony whereof I have signed this preventing the escape of pressure fluid specification. therebetween, a passage in said plate for ad- SNOWDEN B. REDFIELD. 

